1. Field of the Invention
This invention relates generally to air bearing sliders that support transducers over moving recording media and, more particularly, to an air bearing slider which exhibits an improved takeoff velocity.
2. Background Description
Conventional magnetic disk drives are information storage devices which utilize at least one rotatable magnetic media disk with concentric data tracks, a read/write transducer for reading and writing data on the various tracks, an air bearing slider for holding the transducer adjacent to the track generally in a flying mode above the media, a suspension for resiliently holding the slider and the transducer over the data tracks, and a positioning actuator connected to the suspension for moving the transducer across the media to the desired data track and maintaining the transducer over the data track during a read or a write operation.
During operation of the magnetic disk drive, the slider is suspended (i.e., xe2x80x9cfliesxe2x80x9d) above the magnetic media disk on a cushion of air. The separation between the slider and the magnetic media disk is referred to as the xe2x80x9cfly height.xe2x80x9d The goal of air bearing slider design is to achieve a minimal fly height without having the slider physically impact the magnetic media disk. Smaller fly heights are desired so that the transducer can distinguish between the magnetic fields emanating from more closely spaced tracks of the magnetic disk media, thereby making possible an increased recording density for the magnetic disk drive.
In so-called xe2x80x9ccontact start-stopxe2x80x9d(xe2x80x9cCSSxe2x80x9d) magnetic disk drive designs, it is common for a region on the surface of the inner diameter of the magnetic media to be referred to as the xe2x80x9clanding zone.xe2x80x9d This is the region from which the slider lifts off when the magnetic media disk begins moving and is the region to which the slider returns when the magnetic media disk ceases moving.
When used with disks that include a landing zone, a slider must achieve lift quickly once the disk has begun moving to clear the disk surface. The longer the slider takes to lift off the surface (i.e., the slower the slider""s take-off velocity), the longer the time (or the number of rotations) that the slider is in contact with the magnetic media disk. The result is increased wear at the interface of the slider and the magnetic media disk. Furthermore, a slider that has a slow take-off velocity also has the added drawback that any collisions between it and the magnetic media disk that occur at the late stages of the take-off process occur at a high velocity. Such high velocity collisions also increase the wear at the interface of the slider and the magnetic media disk.
The prior art has addressed the problem of achieving a desired take-off, or clearance between the slider and the magnetic media disk. For example, U.S. Pat. No. 5,418,667 to Best et al. entitled SLIDER WITH TRANSVERSE RIDGE SECTIONS SUPPORTING AIR-BEARING PADS AND DISK DRIVE INCORPORATING THE SLIDER (xe2x80x9cthe Best ""667 Patentxe2x80x9d) discloses an air bearing slider pad which rests on a step surface and which is angled to provide extra air bearing lift to the slider at the inner diameter of the magnetic media disk. U.S. Pat. No. 5,870,250 to Bolasna et al. entitled METHOD AND APPARATUS FOR IMPROVING FILE CAPACITY USING DIFFERENT FLYING HEIGHT PROFILES discloses different embodiments of air bearing sliders which use angled rails to create desired air pressure distributions at predetermined radii of a recording medium. Similarly, U.S. Pat. No. 5,796,550 to O""Sullivan et al. entitled METHOD AND APPARATUS FOR PROVIDING DIVERGING RAIL EDGE GEOMETRY FOR AIR BEARING SLIDER discloses a slider having air bearing pads or rails that have at least one edge diverging from the side edges of the pads or rails support structure to reduce the slider""s sensitivity to skew and roll.
The prior art has also addressed the problem of the altitude sensitivity of the fly height air bearing sliders. U.S. Pat. No. 5,777,825 to Dorius entitled NEGATIVE PRESSURE STEP PAD AIR BEARING DESIGN AND METHOD FOR MAKING THE SAME (xe2x80x9cthe Dorius ""825 Patentxe2x80x9d) discloses several embodiments of an air bearing slider which use front and back air bearing surface pads that rest on leading and trailing step surfaces. According to the Dorius ""825 Patent, prior art air bearing slider designs exhibit sensitivity to changes in altitude. This sensitivity poses a reliability problem for magnetic disk drives in that a decrease in a slider""s fly height caused by an increase in altitude results in more interactions between the slider and the magnetic media disk of the magnetic disk drive. Consequently, the incidence of magnetic disk drive failures increases with increases in altitude. The Dorius ""825 Patent is directed to providing an air bearing slider which possesses a reduced sensitivity to changes in altitude. The air bearing slider design described in the Dorius ""825 Patent takes a step-pad (i.e., bobsled) design and adds a negative pressure (i.e., subambient pressure) pocket between the leading-edge and trailing edge pads of the slider. The slider is described as requiring only two etch depths to manufacture, and the negative pressure pocket is described as being etched to a specific depth to achieve the desired reduction in altitude sensitivity.
The prior art has not, however, addressed the problem of improving the take-off velocity of an air bearing slider relative to its take-off location on the disk and its target fly height at that location, i.e., its xe2x80x9ctruexe2x80x9d take-off velocity. The Best ""667 Patent, for example, is directed to achieving a clearance between the slider and the magnetic media disk, but it does not address the problem of achieving an improved (i.e., faster) take-off velocity for the slider. The Dorius ""825 Patent, by way of another example, is strictly directed to improving the altitude sensitivity of sliders, and also does not recognize the need to improve the take-off velocity of air bearing sliders. Nor does the Dorius ""825 Patent recognize the need to balance the altitude sensitivity of a slider with its take-off velocity. Accordingly, there is a need in the art for an air bearing slider that has an improved take-off velocity.
The present invention is directed to an apparatus that satisfies the need for an air bearing slider that has an improved take-off velocity. According to the embodiments of the present invention, the time (or the number of rotations) during which the slider is in contact with the magnetic media disk is reduced.
According to an embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first etched region having a first etch depth and a second etched region having a second etch depth, wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 100%.
The second etch depth may provide a predetermined altitude ratio for the air bearing slider, and may generally be in the range of approximately 500 nanometers to approximately 3000 nanometers. The first etch depth may be shallow in relation to the second etch depth, and may generally be in the range of approximately 50 nanometers to approximately 300 nanometers. The etch depth ratio may be less than or equal to 10%. The second etched region may comprise a negative pressure region.
The air bearing slider may further comprise a pad, and the first etched region may comprise a ramp for compressing air flow incident on the pad. The ramp may comprise a step ramp. The second etched region may comprise a negative pressure region. The negative pressure region may be defined by the pad. The pad may have a generally horseshoe shape.
According to another embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium wherein the air bearing slider lifts off from the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first pad having a first ramp surface for compressing air flow incident on the first pad, the first pad defining a negative pressure region of the slider; a second pad having a second ramp surface for compressing air flow incident on the second pad; and a third pad having a third ramp surface for compressing air flow incident on the third pad; wherein the second and third ramp surfaces are formed at a first etch depth and the negative pressure region is formed at a second etch depth such that the etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 100%.
The second etch depth may provide a predetermined altitude ratio for the air bearing slider. The first etch depth may be shallow in relation to the second etch depth. The etch depth ratio may be less than or equal to 10%.
The first pad may be formed at a leading edge of the air bearing slider. The second pad may be formed at a trailing edge of the air bearing slider. The third pad may be formed at a trailing edge of the air bearing slider. The ramp surfaces may comprise stepped contours. The first pad may generally form a horseshoe shape.
According to a further embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: at least one rail provided with a first etched region along a side edge, the first etched region having a first etch depth; and a second etched region having a second etch depth; wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 80%.
The second etch depth may provide a predetermined altitude ratio for the air bearing slider. The first etch depth may be shallow in relation to the second etch depth. The etch depth ratio may be less than or equal to 10%. The first etched region may comprise a stepped contour.
According to yet another embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of the air bearing slider to a first etch depth, etching a second region of the air bearing slider to a second etch depth, and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a predetermined take-off velocity ratio.
The etch depth ratio may be chosen to be less than or equal to 10%.
The second etch depth may be chosen to provide the slider with a predetermined altitude ratio.
The second etching step may comprise etching the second region to form a negative pressure region. The etch depth ratio may be chosen to provide a take-off velocity ratio greater than or equal to 100%.
The first etching step may comprise etching the first region to form a ramp for a pad of the air bearing slider. The first etching step may further comprise etching the first region such that the ramp forms a stepped contour. The second etching step may comprise etching the second region to form a negative pressure region. The etch depth ratio may be chosen to be less than or equal to 10%.
According to a further embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: forming a first pad having a first ramp surface for compressing air flow incident on the first pad, the first pad defining a negative pressure region of the slider; forming a second pad having a second ramp surface for compressing air flow incident on the second pad; and forming a third pad having a third ramp surface for compressing air flow incident on the third pad; wherein the ramp surfaces are formed by etching to a first etch depth and the negative pressure region is formed by etching to a second etch depth; and choosing an etch depth ratio of the first etch depth to the second etch depth that provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 100%.
The etch depth ratio may be chosen to be less than or equal to 10%. The second etch depth may be chosen to provide a predetermined altitude ratio.
The first forming step may comprise forming the first pad at a leading edge of the air bearing slider. The first forming step may comprise the step of forming a generally horseshoe shape. The second forming step may comprise forming the second pad at a trailing edge of the air bearing slider. The third forming step may comprise forming the third pad at a trailing edge of the air bearing slider. The second and third forming steps may comprise forming ramp surfaces that have stepped contours.
According to an even further embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of the air bearing slider to a first etch depth, etching a second region of the air bearing slider to a second etch depth deeper than first etch depth to provide a desired altitude ratio, and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a predetermined combination of the altitude ratio and a take-off velocity ratio.
The etch depth ratio may be chosen to be less than or equal to 10%.
According to a further embodiment of the present invention, a method for fabricating an air bearing slider, the method comprising the steps of: etching an edge of a rail to provide a first region of the air bearing slider at a first etch depth; etching a second region of the air bearing slider to a second etch depth; and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a predetermined take-off velocity ratio.
The etch depth ratio may be chosen to be less than or equal to 10%.
The first etching step may comprise etching the first region to form a stepped contour.
The second etch depth may be chosen to provide the slider with a predetermined altitude ratio. The second etching step may comprise etching the second region to form a negative pressure region.
The etch depth ratio may be chosen to provide a take-off velocity ratio greater than or equal to 80%.
According to another embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first etched region having a first etch depth that is greater than or equal to approximately 50 nanometers; and a second etched region having a second etch depth; wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to approximately 70%.
The first etch depth may be less than or equal to approximately 300 nanometers. The second etch depth may be in the range of approximately 500 nanometers to approximately 3,000 nanometers. The etch depth ratio may be less than or equal to 15%.
According to yet another embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first etched region having a first etch depth; and a second etched region having a second etch depth that is greater than or equal to approximately 500 nanometers; wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 70%.
The second etch depth may be less than or equal to approximately 3000 nanometers. The first etch depth may be in the range of approximately 50 nanometers to approximately 300 nanometers. The etch depth ratio may be less than or equal to 15%.
According to a further embodiment according to the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of the air bearing slider to a first etch depth that is greater than or equal to approximately 50 nanometers; etching a second region of the air bearing slider to a second etch depth; and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a take-off velocity ratio that is greater than or equal to approximately 70%.
The first etch depth may be less than or equal to approximately 300 nanometers. The second etch depth may be in the range of approximately 500 nanometers and approximately 3000 nanometers. The etch depth ratio may be chosen to be less than or equal to 15%.
According to an even further embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of said air bearing slider to a first etch depth; etching a second region of aid air bearing slider to a second etch depth that is greater than or equal to approximately 500 nanometers; and choosing an etch depth ratio of said first etch depth to said second etch depth to provide said air bearing slider with a take-off velocity ratio that is greater than or equal to approximately 70%.
The second etch depth may be less than or equal to approximately 3000 anometers. The first etch depth may be in the range of approximately 50 anometers and approximately 300 nanometers. The etch depth ratio may be chosen to be less than or equal to 15%.